1. Field of the Invention
The present invention relates to a sealing mechanism for a tubular body.
2. Description of the Related Art
Brazen pipes or the like are hermetic seal tested. These hermetic seal tests verify the hermeticity of the pipe by blocking all of the openings of the pipe with hermetic plugs, injecting air at a predetermined pressure into the pipe, and then measuring the pressure after a predetermined period of time using a pressure gauge.
The hermetic plugs used for these hermeticity tests may for instance be made by retaining a cylindrical rubber body between end plates, passing a shaft member with a hole in the center through the center of the end plates and the rubber body, securing the leading end of the shaft member to one end plate, fitting the shaft member into a pipe, causing the other end plate to contact the leading end of the pipe, and screwing a nut to the shaft member positioned at the back end of the pipe. To illustrate, refer to Japanese Patent Application Laid-Open No. 2002-171654 (FIG. 3 and FIG. 4).
With the hermetic plug of this referenced patent application (Japanese Patent Application Laid-Open No. 2002-171654), the rubber body is inserted to the inside of the pipe from the open end, and both ends are moved towards each other inside the pipe by tightening the nut, and thereby the rubber body will expand outward in the radial direction, creating a press fit between the rubber body and the inside surface of the pipe in order to seal the opening of the pipe.
Note, compressed air is injected into the pipe through the hole in the shaft member.
However, when a pipe opening is sealed with a hermetic plug according to the referenced patent application and then the hermetic plug is to removed, the nut must be loosened each time and this operation is complex.